Abstract:
Three types of effluent from rubber factory: block rubber STR5L, concentrated latex and mixed effluent from block rubber and concentrated latex factory were used. Both chemical and biological tretments were attempted for these effluents. Chemical treatment was done by adjusting pH of effluent = 10 by Ca(OH)2 and coagulation of rubber particles and inorganic salts by ferric chloride, anionic polymer and cationic polymer respectively. BOD and SS of effluent from STR5L factory and mixed effluent are in the range of 4,000-6,000 mg/L and 1,000-1,600 mg/L. After chemical treatment, BOD and SS decrease to 2,700-2,800 mg/L and 100-300 mg/L respectively with the cost of 30 baht/m3. For effluent from concentrate latex factory, BOD and SS were reduced from 200 and 2,000 mg/L to 70 and 70 mg/L respectively at the cost of 25 baht/m3. In all 3 types of effluent chemical treatment show 90% efficiency in removing colloid and rubber particles, 97% phosphate and 84% zinc respectively. The disadvantage of this method is high hardness of post treatment effluent water. Separation of the micro-organisms from 3 types of rubber effluent and characterization resulted in 4 major Genera: Pseudomonas sp. Kurthia sp. Bacillus sp. and Moraxella sp., which grow well in aerobic condition. Biological treatment by using these bacteria with aeration for effluent from concentrate latex factory was therefore used. At optimum aeration rate (1.5 vvm), BOD and SS can be reduced to 70 and 65 mg/L. The resulting BOD, SS and Zn concentration in post treatment effluent, either by chemical or biological method were still higher than the Industrial Effluent Standards which are 60, 50 and 5 mg/L respectively. A new approach is to treat the effluent from concentrated latex factory by applying serum, separated from effluent of skim latex for mushroom, Pleurotus sajor-caju cultivation. Addition of 2-10% serum can increase the productivity of mushroom (g fresh wt of fruiting body) about 25% in basic culture medium (rubber-sawdust:water = 100:20). The optimum concentration of serum, 3% and 5% rice bran can significantly increase productivity of mushroom about 30% comparing with normal culture medium (basic medium + 5% rice bran + 0.3% urea). The average zinc concentration in mushroom was about 60 mg/kg fresh wt, which is lower than the acceptable value, 100 mg/kg food declared by the Ministry of Public Health, 1968. In conclusion the serum fraction of effluent water from concentrated latex factory can be applied for mushroom cultivation.